Meet Wine’s Worst Enemy, Phylloxera

Starting around 1860, a tiny yellow louse called phylloxera (pronounced fi-lok-SUH-ruh) decimated Europe’s vineyards, brought to the continent unknowingly by Victorian-era botanists through American native vines. The pests had free rein on a continent where they never should have set wing. When the damage was done, vineyards throughout the world would be changed forever.

Phylloxera / Getty

How phylloxera spread

“The implication is that phylloxera got into the nursery system early on,” says M. Andrew Walker, Ph.D., a grape breeder, geneticist and professor of viticulture and enology at University of California, Davis.

The louse has two life cycles, “above and below ground, and with an occasional bridge between the two.” Eggs overwinter either in the soil or resting above it. After they hatch, louses below ground feed on a vine’s roots. Those above ground feast on leaves. “Some fall to the ground and crawl back to the roots,” says Walker.

The damage done by subterranean phylloxera allows for soilbourne fungi to enter the wounds and kill the roots. Meanwhile, the lice on the leaves help spread the epidemic. They can be blown by wind to another plant: “They hang-glide more than flap their wings,” says Walker.

Phylloxera starts reproducing two to four weeks after their first meal. Some species lay one egg that will overwinter, other parthenogenic phylloxera lay up to 200 eggs that will hatch within a month. This means multiple generations occur throughout the growing season.

Adding to the problem was how vineyards were arranged. Vineyards were wilder and dense, with more field blends than a single variety. Growers propogated vines through tip layering, where shoots are bent back into the earth to grow new roots. The neat rows of vines you see today and organized blocks were created in response to the phylloxera epidemic. More space between vines translates to fewer chances for pests to spread, and it’s easier for a grower to catch issues faster.

By 1878, the invasion had killed 915,000 acres, while another 620,000 acres were dying. That represented more than 25% of France’s vineyard acreage. Phylloxera penetrated northward until 1895, and French wine production decreased by half.

Panic ripped through France. Thousands of vintners fled the country, convinced that winemaking there was doomed. The government offered a 300,000-franc reward to whomever could solve the epidemic. In the Marne region, residents rang church bells in terror when the pests arrived on their vines.

An 1890 comic of phylloxera / Getty

The cure for phylloxera

Indeed, it would have been the end of French wine (some argue that it was) if American rootstocks weren’t grafted onto Europe’s Vitis vinifera vines. Because phylloxera is American, the rootstocks there had spent generations warding off the pests.

In 1870, Charles V. (C.V.) Riley, a Francophie entomologist in Missouri, identified the characteristics of phylloxera from a French report and theorized a solution that would involve more American rootstock.

Experiments in southern France vineyards began in the 1870s with success validating the theory. Producers in Bordeaux agreed to grafting in 1881 and Burgundy vintners in 1887, despite those who thought French vines shouldn’t be sullied by American rootstocks. Different regions and soil types required different approaches, and French scientists tested thousands of grafting combinations. The winner for the most resistant vines? Vitis rupestris and Vitis riparia.

It took a Texan, Thomas Volney Munson, to save the southwest France’s region of Charente, where Cognac is located. Its chalky soils didn’t respond to American imports. A delegation headed by Montpellier’s Pierre Viala visited Munson at his home in Denison, Texas. They rode on horseback to search for a more hearty, phylloxera-resistant species.

Munson, a viticulturist, managed a French-American graft using Texan rootstocks. He received France’s high honor, the Chevalier du Mérite Agricole, in 1883. The French government also presented C.V. Riley with a Legion of Honor award in 1889.

Phylloxera outside of Europe

The insect also hit Australia hard, beginning in 1875, after European varieties were imported. In recent years, many Australian states have been declared “Phylloxera Exclusion Zones,” where the bug has not yet been detected.

In South Africa, phylloxera arrived in 1886. South African producers quarantined American rootstocks for grafting. Like Australia, some sources trace South Africa’s 1800s outbreak to a particular vintner’s backyard, something akin to blaming Mrs. O’Leary’s cow for the Great Chicago Fire.

In 1937, a mother block of rootstock was created to prepare for another infestation, but then was largely ignored, says Anton Nel, oenology lecturer at Cape Peninsula University of Technology. He has taken it upon himself to save the mother block in case of another epidemic.

“We don’t know why [the insects] don’t feed on sandier sites,” says Walker. In California’s San Joaquin Valley, a vineyard is split by a river. Walker says that the sandy bank is phylloxera-free, but an infestation marred the other side.

Phylloxera still rears its exoskeletal head. In the 1980s, Napa Valley experienced a scare, thanks to the failure of rootstock AXR-1. A resulting infestation spread into Oregon and Washington.

“Although we have had great success using the resistant rootstocks like St. George clone, the possibility of our modern rootstocks succumbing to phylloxera is something we keep in mind as we plan for the future of our vineyards,” says Seth Schwebs, senior viticulturist at Robert Mondavi Winery. “Any new planting in Napa uses these resistant rootstocks, although there are areas in the U.S. that can get away with using own-rooted [ungrafted] vines, like Eastern Washington, which benefits from the Cascade Mountain barrier.”

Today, tastings of wine derived from ungrafted rootstock prove precious, as only a handful of places can do so. For example, few plots in Champagne resisted the insect. Bollinger keeps two vineyards of Pinot Noir, Clos Chaudes Terres and Clos St.-Jacques, going behind protective walls and regularly replanted. Today its Vieilles Vignes Françaises bottling is a cult offering from about a single acre. A third unwalled vineyard, Croix Rouges, succumbed in 2004.

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